Exemplary embodiments of the invention relate to a crash-tolerant system arrangement in an engine compartment situated in the front end region of a motor vehicle.
In order to increase occupant protection, in particular for the case of a front-end collision, it is known to provide the front end region with energy-absorbing structures that are sufficiently deformable under the action of force. For example, German patent document DE 102009016941 A1 discloses a crash-tolerant system arrangement in an engine compartment situated in the front end region of a motor vehicle, where the system arrangement has energy absorption elements associated with an exhaust gas system of the motor vehicle. However, the requirement for providing the most compact systems possible that can be accommodated in a confined space in an engine compartment despite a high level of complexity makes it difficult to use crash-tolerant energy absorption elements, since these elements usually provide an energy-absorbing deformation path, which entails increased installation space requirements.
Exemplary embodiments of the present invention are directed to a system arrangement in an engine compartment situated in the front end region of a motor vehicle that is both crash-tolerant and compact.
The system arrangement according to the invention comprises an internal combustion engine situated in the engine compartment and having an engine block, an exhaust gas manifold that receives exhaust gases of the internal combustion engine, an exhaust gas turbocharger, associated with the internal combustion engine, having an exhaust gas inlet and an exhaust gas outlet, and an exhaust emission control system having an essentially cylindrical first catalytic converter housing that is situated in front of the exhaust gas turbocharger in the travel direction and in which a first exhaust gas catalytic converter element is situated. Characteristically, a first exhaust gas conducting element for conducting exhaust gas from the exhaust gas outlet of the exhaust gas turbocharger to the first catalytic converter housing is provided, and extends from the exhaust gas outlet of the exhaust gas turbocharger to an inlet funnel of the first catalytic converter housing and is able to transmit a pressure force, which acts on the first catalytic converter housing essentially opposite to the travel direction, at least partially to the exhaust gas turbocharger. The exhaust gas turbocharger is mechanically connected to the exhaust gas manifold via a first fastening device, and to the engine block via a second fastening device, the first and the second fastening devices being designed in such a way that a detachment of the connection of the exhaust gas turbocharger to the exhaust gas manifold and/or a detachment of the connection of the exhaust gas turbocharger to the engine block take(s) place within a predefined upper value range for the pressure force.
Due to this design of the fastenings of the exhaust gas turbocharger to the internal combustion engine, when an impact force which acts, in particular approximately frontally, on the first catalytic converter housing, an energy-absorbing displacement of the first catalytic converter housing that is coupled to the exhaust gas turbocharger is achieved without portions of the exhaust emission control system being pushed into the vehicle interior. This design has proven to be particularly advantageous for an internal combustion engine or engine block, which characteristically has multiple cylinders arranged in succession and which is situated lengthwise in the engine compartment in the travel direction, in particular when a front end of the first catalytic converter housing, viewed in the travel direction, is situated in front of a front end of the engine block. An impact force acting approximately frontally thus initially acts in an energy-absorbing manner on the exhaust emission control system, and action on the engine block, which could move the engine block toward the passenger compartment, is avoided. The design of the fastenings of the exhaust gas turbocharger with a defined strength assures targeted detachment of the turbocharger to which the first catalytic converter housing is fastened via the first exhaust gas conducting element, and thus allows a further force-absorbing displacement of the first catalytic converter housing, thereby avoiding blockage. The dimensioning and the design of the turbocharger fastenings determine the magnitude of the pressure force, acting on them, which causes detachment of the connections to the turbocharger.
The fastening device for connecting the exhaust gas turbocharger to the engine block is preferably designed as a retaining plate that is profiled, and which via a screw connection is fastened on the one hand to the engine block, and on the other hand to the exhaust gas turbocharger housing or to its turbine housing. A detachment of the connection of the exhaust gas turbocharger to the engine block due to a collision-related action of force preferably takes place via a detachment of the screw connection of the mounting to the turbine housing. The fastening device for connecting the exhaust gas turbocharger to the exhaust gas manifold is preferably designed as a detachable line connection, for example in the form of a quick-release coupling. It has proven to be particularly advantageous for the crash characteristic that, after the exhaust gas turbocharger detaches from the internal combustion engine due to the detached connections of the exhaust gas turbocharger, a further energy-absorbing displacement or deformation of portions of the exhaust emission control system and in particular of the first catalytic converter housing is made possible. The fastening devices are preferably designed in such a way that, under an action of force of increasing magnitude, the connection of the exhaust gas turbocharger to the exhaust gas manifold is detached prior to detachment of the connection to the engine block. In order for an impact force that acts approximately frontally to be effectively transmitted from the first catalytic converter housing to the exhaust gas turbocharger via the first exhaust gas conducting element, the exhaust gas turbocharger is preferably situated in such a way that its exhaust gas outlet is oriented toward the front in the travel direction. In addition, the first exhaust gas conducting element preferably extends, at least in part, approximately linearly from the exhaust gas turbocharger outlet to the inlet funnel of the first catalytic converter housing.
In one embodiment of the invention, the first exhaust gas conducting element has a bellows section that undergoes a reduction in length by at least 20 mm within a predefined lower value range for the pressure force, the values of the lower value range being smaller than the values of the upper value range. The bellows section thus has a comparatively soft design. In this way, energy-absorbing deformation is advantageously made possible before a further increase in the action of force results in destruction or detachment of the provided connections of the exhaust gas turbocharger. In addition to force absorption in the event of a collision, during normal operation the bellows section also advantageously brings about decoupling or damping of vibrations emanating from the engine block. The bellows section may also be designed for reductions in length of greater than 20 mm. Maximum length reduction distances of up to 40 mm are considered advantageous.
In another embodiment of the invention, the first and second fastening devices are designed in such a way that a detachment of the connection of the exhaust gas turbocharger to the exhaust gas manifold and/or of the connection of the exhaust gas turbocharger to the engine block takes place under a pressure force of less than 40 kN. The upper limit of the upper value range for the pressure force acting on the first catalytic converter housing is thus 40 kN. However, a detachment of the connections may be provided for lower values down to approximately 20 kN. An appropriate design may be provided, for example, by a connection, screwed down with an appropriate tightening force, of the turbine housing in a yoke hole receptacle of the retaining plate, in which the screw is pushed out of the yoke hole under the action of the pressure force. With regard to a detachment of the connection to the exhaust gas manifold caused under a defined action of force, for the case of a quick-release coupling, for example, a predefined strength of the quick-release bracket may be provided. It has been found by the present inventors that such a design allows particularly efficient utilization of deformation energy.
In another embodiment of the invention, an upper limit of the lower value range for the pressure force is 30 kN. A maximum reduction in length of the bellows section is thus achieved at the latest when the pressure force is 30 kN. This design ensures that damage remains limited in the event of a minor collision.
In another embodiment of the invention, the first catalytic converter housing is situated at least approximately vertically in the engine compartment. Use is thus advantageously made of the fact that the housing has less rigidity or strength in the radial direction than in the axial direction. An impact force acting approximately frontally on the first catalytic converter housing may thus be absorbed in an improved manner. In addition, the vertical arrangement of the first catalytic converter housing allows a particularly compact design of the exhaust emission control system.
In another embodiment of the invention, the first catalytic converter housing has a ribbed structure, at least in part. As a result of this design, the first catalytic converter housing has reduced rigidity in the direction of the action of force, and allows energy-absorbing deformations in an improved manner.
In another embodiment of the invention, the exhaust emission control system has a cylindrical second catalytic converter housing in which a second exhaust gas catalytic converter element and/or a particle filter element is/are situated, a second exhaust gas conducting element for conducting exhaust gas from the outlet side of the first catalytic converter housing to the inlet side of the second catalytic converter housing being provided which at a separation point is detachably connected to an inlet funnel of the second catalytic converter housing. As the result of providing a further exhaust emission control element having filtering and/or catalytic activity, the efficiency of the exhaust aftertreatment system is improved or expanded, and due to the detachable connection, provided with a separation point, of the second catalytic converter housing to the first catalytic converter housing, further latitude in the displacement or deformation is made possible when this connection is detached, which likewise has an energy-absorbing effect and increases the collision tolerance. This effect may be further enhanced when, in another embodiment of the invention, the second exhaust gas conducting element has a ribbed design, at least in part, or has a bellows section.
In another embodiment of the invention, a structural modification acting as a predetermined bending point is provided in a transition area from the second exhaust gas conducting element to the second catalytic converter housing. The predetermined bending point enables a targeted directed bending, thus avoiding a blockage-forming orientation of the first and second catalytic converter housings, in the sense of increasing the strength under the action of a force acting opposite to the travel direction. The predetermined bending point is preferably provided close to a transition between the second exhaust gas conducting element and an inlet funnel of the second catalytic converter housing, and may be achieved by means of an indentation, for example.
In another embodiment of the invention, the second catalytic converter housing is situated at least approximately horizontally in the engine compartment and geodetically underneath the exhaust gas turbocharger, and viewed in the travel direction, behind the first catalytic converter housing and with little or negligible lateral offset with respect to the first catalytic converter housing, in such a way that the top side of the second catalytic converter housing is in the range of the geodetic height of the first catalytic converter housing. The first and second catalytic converter housings are thus situated on the same side of the engine block. In conjunction with the vertical arrangement of the first catalytic converter housing, the horizontal arrangement of the second catalytic converter housing underneath the exhaust gas turbocharger results in a particularly compact design of the exhaust emission control system. Due to this arrangement, the routing of exhaust gas exiting from the first catalytic converter housing undergoes a deflection by at least approximately 90 degrees prior to entering the second catalytic converter housing. This facilitates energy-consuming bending of the second exhaust gas conducting element under the action of an impact force directed opposite to the travel direction.
In another embodiment of the invention, the second catalytic converter housing is connected to the engine block in a force-fit and/or form-fit manner on the exhaust gas inlet side via a first mounting, and on the exhaust gas outlet side via a second mounting, the first mounting having a lower flexural strength than the second mounting, viewed in the travel direction. The first mounting thus allows an energy-absorbing movement, in particular opposite to the travel direction, of components connected to the first mounting. The more rigid design of the second mounting crucially hinders the second catalytic converter housing, which is comparatively rigid in the longitudinal direction, from penetrating into the passenger compartment under the action of a frontal collision force.
In another embodiment of the invention, a flat material component whose surface normal is oriented at least approximately perpendicularly with respect to the travel direction is provided in the area between the first catalytic converter housing and the second catalytic converter housing. This allows the first catalytic converter housing and the first exhaust gas catalytic converter element situated therein to be destroyed by the flat material when the action of the pressure force causes the first catalytic converter housing to be pushed onto the second catalytic converter housing. As a result of the destruction, the rigidity of the first catalytic converter housing is drastically reduced, thus avoiding blockage formation and allowing further energy-absorbing deformation. For particularly effective functioning of the flat material in the sense mentioned, it is advantageous for the surface normal of the flat material to be oriented vertically or approximately vertically. The flat material is advantageously fastened to the second catalytic converter housing, and, for example, may be an integral part of a mounting.
In another embodiment of the invention, a retaining part for the first and/or the second catalytic converter housing is provided in the area between the first catalytic converter housing and the second catalytic converter housing, the retaining part having a geodetically inclined, upwardly directed sliding surface with respect to the travel direction, which allows the first catalytic converter housing to be pushed onto the second catalytic converter housing. A blockage formation of the first and second catalytic converters housing when acted on by an appropriately large impact force is thus avoided, since a further escape path is provided to the first catalytic converter housing.
In another embodiment of the invention, the first catalytic converter housing and/or the second catalytic converter housing is/are made, at least partially, preferably predominantly, of a metal material having a material thickness of less than 1 mm. The design of the housing material as a thin metal sheet reduces the rigidity of the housing, thus allowing deformation with corresponding energy absorption in a particularly effective manner.
In another embodiment of the invention, the first catalytic converter housing is connected to the second exhaust gas conducting element via a weld seam, the weld seam having a predetermined breaking point which allows the weld seam to rupture when a tensile force of a predefined magnitude acts on the predetermined breaking point. As a result, when acted on by an impact force of a certain magnitude, the first catalytic converter housing detaches from the second exhaust gas conducting element. Further displacement of the first catalytic converter housing is thus enabled, for the most part independently of its connection to the second catalytic converter housing, and a blockage formation which has a rigidifying effect is likewise avoidable.